Java Decompressing byte array - incorrect data check

Question

I have a little problem: I decompress byte array and everything is ok with following code but sometimes with some data it throws DataFormatException with incorrect data check. Any ideas?

 private byte[] decompress(byte[] compressed) throws DecoderException {
    Inflater decompressor = new Inflater();
    decompressor.setInput(compressed);
    ByteArrayOutputStream outPutStream = new ByteArrayOutputStream(compressed.length);
    byte temp [] = new byte[8196];
    while (!decompressor.finished()) {

        try {
            int count = decompressor.inflate(temp);
            logger.info("count = " + count);
            outPutStream.write(temp, 0, count);
        }
        catch (DataFormatException e) {
            logger.info(e.getMessage());
            throw new DecoderException("Wrong format", e);
        }
    }
    try {
        outPutStream.close();
    } catch (IOException e) {
        throw new DecoderException("Cant close outPutStream ", e);
    }
    return outPutStream.toByteArray();
}

It seems that the compressed data can't pass the Adler32 check. The simplest solution is to use nowrap option when initializing Inflater and remove the first two bytes in compressed data. — Roaid
– Roaid, Commented Jun 14, 2021 at 9:17

Filippo Fratoni · Accepted Answer · 2015-12-18 11:11:25Z

1

Try with a different compression level or using the nowrap options

answered Dec 18, 2015 at 11:11

Filippo Fratoni

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Comments

Community · Accepted Answer · 2017-05-23 11:53:37Z

1

1 Some warning: do you use the same algorithm in both sides ?

do you use bytes ? (not String)

your arrays have the good sizes ?

2 I suggest you check step by step, catching exceptions, checking sizes, null, and comparing bytes.

like this: Using Java Deflater/Inflater with custom dictionary causes IllegalArgumentException

Take your input
Compress it
copy your bytes
decompress them
compare output with input

3 if you cant find, take another example which works, and modify it step by step

hope it helps

edited May 23, 2017 at 11:53

CommunityBot

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answered Dec 18, 2015 at 11:41

guillaume girod-vitouchkina

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1 Comment

rzeznik Over a year ago

problem is that i do not compress it, i have just compressed value via Go lang

rzeznik · Accepted Answer · 2015-12-21 16:58:57Z

0

I found out why its happening byte temp [] = new byte[8196]; its too big, it must be exactly size of decompressed array cause it was earlier Base64 encoded, how i can get this size before decompressing it?

answered Dec 21, 2015 at 16:58

rzeznik

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